The present invention relates to a new and improved construction of a ground covering containing adjoining plates which are fastened to one another or interlocked by means of tensioning or tightening elements which extend essentially parallel to the plates and through such plates, there also being provided positive locking elements arranged between neighboring plates and effective transversely to the plane of the plates.
In the context of this disclosure the term "ground covering" or equivalent expression, is employed in a broader sense to encompass not only a covering for the ground, but also for other surfaces where such covering might be used.
Such type of ground coverings are particularly used, although not exclusively, in factories, storage areas or warehouses, roller skating rinks and other sport establishments, streets, namely provisional streets or streets designed to have a limited life, runways for aircraft, also runways for sport planes, supply and military aircraft, inclusive of helicopters, and which runways are intended to be provisionally erected or temporarily used. The acceptance of such ground coverings is predicated upon the fact that the plates which can be advantageously prefabricated can be quickly laid, require a comparatively modest amount of preparation and can be immediately used after laying of the ground covering.
Now in Swiss Pat. No. 386,082 there is disclosed one such prior art ground covering. It is composed of square plates. Through each plate there are drawn pairs of tightening or tensioning elements which extend at right angles to one another, and by means of such tensioning elements the plates can be interconnected in their plane into a comparatively rigid structure. Formed at two of the narrow sides of each plate are tongues of trapezoidal shape in cross-section, these tongues engaging into a respective one of two grooves which are formed at both of the remaining narrow sides of the neighboring plates. The groove-and-tongue connection constitutes a positive of form locking element which is effective transversely to the plane of the plates.
However, this state-of-the-art ground covering is associated with different drawbacks. As is known it is unavoidable that individual plates of the composite structure will rupture, whether such be due to overload, because of a local dropping of the ground or owing to the effects of frost or other adverse weather conditions. Yet, a broken or ruptured plate constitutes a non-inconsequential risk for the vehicles or the like which travel upon the ground covering. With this prior art ground covering replacement of an individual broken plate is not possible because of the groove-and-tongue connection, without dismantling an appreciable part of the entire ground covering.
Furthermore, the heretofore known ground covering can only adapt itself to a limited degree to dropping or sinking of the ground and the ground and can only adapt itself to a limited extent for snugly nesting against changing shapes of the ground, without there arising breaking-out of the tongue and/or the groove, which, in turn, can cause similar adverse consequences, such as rupture of a plate.
In addition to the foregoing, there is further to be considered the fact that exactly in its most preferred fields of application the prior art ground or floor covering affords a practically tight covering of the ground upon which it is laid. In other words, apart from at the region of its edges, the heretofore known ground covering does not provide practically any drainage possibility for rain water, so that so-to-speak there unavoidably are produced water pools or puddles, not even considering the disturbances which are caused by the ground water beneath the covering.